The present invention relates to microwave transceivers and, more particularly, to those using the technique of printed circuits for their transmission/reception and microwave filtering unit and for their modulation-demodulation unit. The making of these two units should take account of the fact that the transmission/reception and the filtering are done at a frequency of some gigahertz while the working frequency of the modulator/demodulator is considerably lower: of the order of 100 kHz.
Given its working frequency, the transmission/reception unit should be entirely shielded and not only should the transmission-reception be electromagnetically insulated from the filtering but also the circuits corresponding to the different functions relating to the transmission-reception should be strictly insulated from one another.
There are known transceivers working in microwave mode wherein, for transmission-reception, each function is carried out on an individual printed circuit. The different printed circuits are embedded in the housings of a metal piece carved from the block or obtained by molding and then machining. One or more lids are screwed on to the metal piece to close the housings. The microwave filter, which is of the type with resonator, is enclosed in a chamber that is formed by two half-shells fixed to the metal piece which contains the transmission-reception unit. The modulation-demodulation unit is mounted on a printed circuit that is proper to it. The internal connections of the transmission-reception and filtering unit are made by holes drilled in the partitions. The connections between the transmission-reception and filtering unit and the rest of the transmitter, including the modulation-demodulation unit, are made by using bypass circuits.
These known embodiments of microwave transceivers have certain drawbacks: owing to the number of parts to be assembled, the operations of mounting and dismantling the devices are lengthy, and there are substantial risks of microwave leakage. Furthermore, the making of the connections between the different printed circuits is a very delicate task.